1. Field of the Invention
This invention relates to a glyceride emulsifier having an elevated diglyceride portion that is especially useful in preparing puff pastry products. The high diglyceride emulsifier is obtained by the interesterification or glycerolysis of triglycerides with glycerol. Triglyceride reacts with glycerol at high temperatures, for example 200-250° C. under alkaline catalysis, yielding a mixture of mono-, di-, and triglycerides, and a small portion of unreacted glycerol. Commercial mono- and diglycerides usually contain 40-60% monoglycerides, 38-45% diglycerides, 8-12% triglycerides, and 1-7% free glycerol. In accordance with this invention, the diglyceride portion w/w is increased to at least about 65% to about 80%, more preferably from about 70% to about 80%, and most preferably to about 74% for example, by vacuum distillation, with the remaining monoglyceride portion being about 10% and the triglyceride portion of the order of 15%. Alternatively, the glycerine to fat ratio is selected to yield the required elevated diglyceride portion.
The high diglyceride emulsifier (herein “HiDi”) is particularly useful in the production of a semi-solid, self-sustaining trans fat free puff pastry margarine prepared from initially liquid non-hydrogenated vegetable oil. Puff pastry bakery goods prepared using the margarine have significantly lower saturated fat content and a substantially higher polyunsaturated fat level than puff pastry prepared from heretofore available mono- and diglyceride emulsifiers.
2. Description of the Prior Art
Puff pastries require the inclusion of a fat-continuous emulsion such as margarine. For use in preparing a puff pastry, the margarine must have certain specific structural characteristics, such as predetermined plasticity, dispersibility, and solid fat content profile, i.e., the percent solid fat present at different temperatures.
In the past natural products such as butter or lard were used as the fat-continuous emulsion for preparation of puff pastry products. For a number of reasons including availability and cost, margarines have more recently been produced from vegetable oils. Since vegetable oils are liquids, they must be given structure by the introduction of solid fat in order to achieve the desired plasticity and solid fat content profile required for functionality. A number of approaches have been employed for generating the solid fatty materials needed to achieve the desired solid fat content profile for the particular temperatures required in puff pastry processing. Two approaches that have been widely practiced in the past involved the partial hydrogenation of the vegetable oil, and/or the addition of solid fatty materials. Oil and solid fat blends have been interesterified to further improve functionality. When a solid fatty material is to be added, that material can be obtained either by hydrogenation of a fat or oil or by fractionation of solid fat from a naturally occurring fat. These approaches are well known among those skilled in the art of preparing fat-continuous emulsions such as margarines.
The structured fats used in the production of fat-continuous emulsions contain saturated fatty acids and unsaturated fatty acids. Naturally occurring unsaturated fatty acids have carbon-carbon double bonds in a cis-configuration. Partial hydrogenation of fat can cause isomerization with some of the carbon-carbon double bonds of the cis-unsaturated fatty acids being converted to the trans configuration. Until recently, trans fatty acids were nutritionally categorized along with cis fatty acids as unsaturated fatty acids without the demonstrated negative health consequences of saturated fatty acids. However, a great deal of research has recently implicated trans fat in the development of cardiovascular disease. Thus, the National Academy of Medicine and many nutritionists have advised that consumption of trans fats be limited as much as possible within the needs of a nutritionally adequate diet. Minimizing the presence of trans fatty acids in the diet requires that the efficient and economically advantageous practice of partial hydrogenation be greatly reduced. Therefore, there is a need for alternative approaches that will permit the structuring of fats for use in fat-continuous emulsions such as margarines without introducing trans fatty acids or increasing the content of saturated fatty acids.
Puff pastries can contribute very significant levels of trans fat to the diets of consumers. This is because the pastries themselves contain 30% or more of fat. The fat compositions used to prepare puff pastry margarine usually have a trans fat content of from 25-35% so that pastries made from such a margarine contain at least about 7.5-10% trans fat.